This invention relates in general to motor vehicle lighting safety systems, and more particularly related to turn signals.
Motor vehicles sold in the United States are required by law to have a turn signal system such that a driver of a motor vehicle is able to signal intentions of an impending turn to other drivers. A secondary function of the turn signal system is that it is used for signaling lane changes on a multilane roadway or a multilane highway. Signaling a lane change before the lane change occurs is courteous to other drivers, reduces the risk of an accident, and is usually required by law in most jurisdictions.
Lane departure warning systems (LDW) and lane departure prevention systems (LDP) have been developed and implemented on motor vehicles where a forward viewing image processing system and computer software detect the dashed and solid painted road lines when they are present and visible. If the vehicle ventures too far out of the original lane of travel, then the driver is instantly alerted by tactile, visual or audible means to the impending unintended lane departure. The driver can then correct the situation by steering the vehicle back into the original lane. In the event of a driver-intended lane change, usage of the turn signal would trigger the LDW system that the lane change is indeed intentional and would therefore not send a warning alert to the driver. A secondary benefit of the LDW system has been advocated which is that the LDW promotes the use of the turn signal for lane changes.
LDW systems are primarily intended for interstate highway use where driving for long periods of time can be somewhat hypnotic to the driver and there is a higher likelihood of an unintended roadway departure due to fatigue and the effects on humans of extended drowse-inducing driving. The LDW warning that is communicated to the driver is intended to be instantaneous, abrupt, and disruptive such that the driver will be immediately alerted in time to take sufficient countermeasures to prevent an accident. In contrast, driving on lower speed multi-lane roadways, such as those typically with posted speed limits below 55 miles per hour are usually less drowse-inducing, in part due to the continuously changing conditions presented to the driver. In situations where there are lower speed limit multi-lane roadways, it remains important that the driver properly utilize the lane change turn signal when changing lanes for reasons of safety and as a courtesy to other drivers. LDW systems are capable of detecting the lanes and lane changes on lower speed roadways, but the instant and abrupt warning is not appropriate because the lack of lane change turn signal on the part of the driver is usually not from a driver dozing condition, but is due to a neglect on the part of the fully alert driver to use the turn signal. Therefore, the startling warning would become viewed as a nuisance to most drivers, not a reminder to use the turn signal when changing lanes. For this reason, most LDW systems to date have been designed such that a minimum vehicle velocity threshold is required wherein the full communication abrupt warning is ready to be activated, and below that velocity, the warning means is either deactivated or is designed to instantly communicate a lesser level of warning. Some manufacturers have designed their systems such that they have no warning what so ever below the threshold velocity, while others, may present a visual warning at each detected lane departure, but do not present the audible or tactile warning that would be present at higher vehicle velocities.
The problem with the methods currently in use in these LDW systems is that some level of warnings are presented each and every time the driver departs the original lane without the use of a turn signal. Ideally in the lower speed circumstances, any warning that would be designed by the manufacturer to alert the driver from a LDW system should be designed as a reminder to use a turn signal when changing lanes rather than how it is designed today where a warning is presented that alerts and/or calls for immediate action from the driver. Warnings of any kind being presented each time at the lower speeds would be considered an excessive distraction to most drivers. There are some circumstances where a turn signal may not necessarily be appropriate and hence the driver could easily become annoyed at a warning system that is relentlessly alerting in every instance. In most vehicles, the LDW system can be selected by the driver to be shut off, and it would be conceivable that a system that is viewed as an annoyance would be promptly shut off by the driver. This action is counterproductive to the goal of encouraging turn signal usage at all speeds with the LDW.
What is needed is a system whereby the LDW communication to the driver at lower vehicle velocities that is not abrupt but is appropriate to encourage and remind the driver of using the turn signal during lane changes without the reminder becoming an annoyance and without occurring in every instance. Such a system would be perceived by the driver as a reminder for future lane changes with turn signal usage and not a warning that calls for immediate action from the driver.